TGF-alpha is synthesized as a transmembrane form (TM TGF-alpha) in most epithelial cells and can bind to the EGF/TGF-alpha receptor similar to its soluble form. However, the regulatory mechanisms that lead to the presentation and function of TM TGF- alpha are not clear yet. This application aims at the molecular and functional characterization of two TM TGF-alpha-associated proteins. Aim 1 is aimed at characterizing the role of p59, which shows structural similarity to the Golgi protein GRASP 65. I will define the structural requirements of its interaction with TM TGF-alpha and characterize the potential roles of p59 on the intracellular routing, surface presentation of TM TGF-alpha, and on the cytoskeletal organization. I will give particular attention on how this association affects polarized transport of TM TGF-alpha in polarized epithelial cells. Aim 2 should result in the isolation and characterization of another TM TGF-alpha- associated protein p86. The structural and functional characterization of the association of p86 with TM TGF-alpha will be studied in similar ways as for p59. These findings, in general, should contribute to an further understanding of how TGF-alpha and related growth factors affect the behavior and physiology of normal and tumor cells.